Sewing-machine tension.



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. -sEwsNG MACHINE TENsloN.

APPLICATION FILED DEC. 4.1911- RENEWED FEB. 18| 1915.

Patented Aug. 81, 1915.

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turen srarrns yr .naar rtl-WE EDWARD ERICKSON, OF WEST LYNN, MASSACHUSETTS, ASSIGNOR, BY DIRECT AND MESNE ASSIGNMENTS, TO VICTOR SHOE MACHINERY COMPANY, 0F BOSTON, MASSA- CIIUSETTS, A CORPORATION OF MASSACHUSETTS.

SEWING-MACHINE TENSION.

4, 1911, Serial No. 663,944.

T0 all whom t may concern Be it known that I, EDWARD ERICKSON, a citizen of the United States, and a resident of iVest Lynn, in the county of Essex and State of Massachusetts, havevinvented certain new and useful Improvements in Sewing-Machine Tensions, of which the follow ing is a specification.

Thisinvention relates to machines for sewing heavy material such as leather, and refers particularly to that type known as welt sewing machines, and to the tension mechanism thereof.

The object of the invention is to provide a simple and effective tension device that will at predetermined times, firmly grip the thread to prevent it from being pulled from the source of supply when the take-up operates; and to this end the invention consists in the construction and combination of parts substantially as hereinafter described and claimed.

As the present application is a division of another application filed by me August 18, 1911, Serial No. 644,7 69, which describes the entire sewing machine, it is sufficient herein to present only two figures of the drawings of such application to illustrate the tension mechanism.

Figure 1 is a plan view of the entire machine, and Fig. 2 is a detail elevation (some parts being shown in section) of the members of the tension mechanism.

The main shaft 33 of the machine is driven by a belt on pulley 34, and by suitable gearing not shown, actuates a vertical shaft 41 which latter, by gearing and connections not necessary to describe herein, operates parts of the stitch-forming mechanism.

To better explain the tension mechanism, the take-up device will be briefly referred to as follows z-On a rock shaft 78 is an eccentric 79 which forms an adjustable fulcrum for the take-up lever 80, said rock shaft and eccentric being shifted according to the thickness of the work as explained in my said application 644,769. The arm 81 of lever 8O is connected by a link 82 with a lever 83 having a roll 84 engaging a cam groove in disk 85 fixed on shaft 33.

specification of Letters Patent.y

Patented Aug. 31, 1915.

Divided and this application filed Decemberl Serial No. 9,209.

The tension mechanism comprises. a rock shaft 169. having an offset arm. 170 and mounted in suitable fixed brackets 171, 172, said. arm 17 0 having two hook-shaped pro- `iections or pins 17 3. Mounted at one end in the bracket 172, and at the other end in the fixedportion of the frame and parallel with the rock shaft 169 is a bar 174 which is preferably cylindrical in form as illustrated. Said bar is fixed, being supported at one end in bracket 172 and at the other end in a portion of the frame, and the bracket 171 is fixedly supported by said bar. A spring 17 5 (see dotted lines Fig. 1) is coiled about the rock shaft 169 and is secured thereto at one end and at the other end engages the bar 174, said spring serving to press the arm 17 O against the bar 174. Preferably the portion of the arm 170 which bears against the thread, is flattened as shown in Fig. 2. rThe needle thread a passes from the source of supply between the arm 170 and the bar 174 preferably passing once around the arm 17 O and between the two hook pins 173, which latter serve to prevent the thread from slipping 0H or out of position. The thread next passes under the arm 174, around a pulley 17 6, under a roll 177 carried by the take-up lever 80 and then over a pulley 178, so that the take-up, when operating, forms a bight or loop of thread between the two pulleys 176, 178. The thread then passes to the mechanism presently described. The spring 17 5 acts with sufficient pressure to cause the tension arm 170 to firmly grip the thread to prevent it from being pulled from the source of supply when the take-up operates and the stitch is being tightened. The spring 175 however may be omitted because, when the thread is passed once around the oE-set arm as described, the pull of the thread itself holds the arm, and the coil of thread, toward the supporting bar 174. The rockshaft 169 has secured thereto an arm 179, the end of which projects into the path of movement of a beveled pin 180, projecting from the vertical shaft 41 (see Eig. 1). Said shaft rotates in the direction of the arrow in Fig. 1 and when the beveled pin 180 passes the end of arm 179, it acts on the latter to rock the shaft 169 in a direction to release the pressure of the tension arm 170, this occurring when the caster is lengthening the loop.

From the pulley 178 the thread passes through an eye 181 in a lever 182 which, as explained in said application 644,769, is actuated to deliver the thread to the hook of the needle.

I claim z* 1. A sewing machine tension comprising a rock shaft having'one end offset to provide a tension arm, said arm having means for retaining thread thereon, a support toward and from which said offset arm is laterally movable, and means for intermittently actuating the rock shaft to shift its arm relatively to said support.

2. A sewing machine tension comprising a rock-shaft having an oifset tension arm provided with a thread-engaging face in a plane substantially parallel with the aXis of the rock shaft, a bar to coperate with said offset arm in pinching the needle thread, 'a spring on the rock shaft and connected to press the offset arm toward said bar, a shaft having a pin, and an arm connected to the rock shaft and extending into the path of said pin whereby the pressure of the offset o tension arm may be released.

In testimony whereof I have afliXed my signature, 1n presence of two witnesses.

EDVARD ERICKSON.

`Witnesses A. WV. HARRISON, J. M. MURPHY.

Copies of this patent may be obtained for ve cents each, by addressing the Commissioner of Patents' f Washington, D. C. 

